为什么我不能得到 /comments/new.html.erb？

Question

我通过脚手架命令创建了模型

class Post < ActiveRecord::Base
  has_many :comments, as: :commentable
end

class Comment < ActiveRecord::Base
  belongs_to :commentable , polymorphic: true
end

...

routes.rb:

 resources :posts, :images, :links do
    resources :comments
 end

comments_controller.rb:

def new
  @comment = Comments.new
end

/posts/show.html.erb:

 <%= link_to 'Add comment', new_post_comment_path (@post)%>

这里我想我需要...(@post, @comment),like from http://guides.rubyonrails.org/routing.html:

<%= link_to 'Ad details', magazine_ad_path(@magazine, @ad) %>

但我这里没有@comment。

我得到错误：

    Showing /home/loza/Projects/my_blog/app/views/comments/_form.html.erb where line #1 raised:

    undefined method `comments_path' for #<#<Class:0x007f2e4a77c2f0>:0x007f2e4ab23ef8>

Extracted source (around line #1): 
<%= form_for(@comment) do |f| %>
  <% if @comment.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@comment.errors.count, "error") %> prohibited this comment from being saved:</h2>

      <ul>

我要怎么写才能得到/comments/new.html.erb？

今天我更正了我的代码： /posts/show.html.erb:

<%= link_to 'New comment', new_post_comment_path(@post, @post.comments.build) %>

/comments_controller.rb:

  def new
    @post = Post.find(params[:post_id])
    @comment = @post.comments.new
  end

我又遇到了同样的错误：

Showing /home/loza/Projects/my_blog/app/views/comments/_form.html.erb where line #1 raised:

undefined method `comments_path' for #<#<Class:0x007fa736859320>:0x007fa73669e238>

xtracted source (around line #1):

  <%= form_for(@comment) do |f| %>
  <% if @comment.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@comment.errors.count, "error") %> prohibited this comment from being saved:</h2>

app/views/comments/_form.html.erb:1:in `_app_views_comments__form_html_erb___1254360398011104975_42800220'
app/views/comments/new.html.erb:3:in `_app_views_comments_new_html_erb__2117553728149416519_42948680'

问题出在哪里？我该如何解决？

Answer 1

如错误所述，您遇到的错误位于 _comments/form.html.erb:

form_for(@comment)

您需要 @post 对象，以便 form_for 找到正确的路径：

form_for([@post, @comment])

Answer 2

这是因为您不仅有 '/comments/new' 路径，而且 form_for(@comment) 正在尝试创建它。

您的路线正在创建类似于 '/post/:id/comments/new' 的路径，因此您必须使用 form_for([@post, @comment])。

同时在新方法中添加 @post = Post.find(params(:is)) 或更好的 before_action 回调。

为什么我不能得到 /comments/new.html.erb？

Why can't I get /comments/new.html.erb?

ruby-on-rails

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